A conventional light-emitting diode (LED) device may be driven by a driving system to adjust an overall brightness thereof. The driving system is coupled to the LED device, and is configured to acquire a number of driving signals each representing a brightness bit associated with a specific level of brightness, and to sequentially transmit the driving signals to the LED device for driving the operation thereof.
FIG. 1 illustrates the driving signals being transmitted to the LED device (not shown). Firstly, a first one of the driving signals (M1) (representing a lowest brightness bit) is to be stored by the driving system and transmitted. The storing and transmitting of each driving signal requires a preparation period (T1). Upon receipt of the driving signal (M1), LEDs of the LED device are each turned on or off for a predetermined driving period (T2). Note that transmission of the driving signal takes up an insignificant amount of time in comparison with the storage of the same, and so in the figure, the preparation period (T1) is labeled to indicate the time for storage only.
For the driving system, after the driving signal (M1) is transmitted, a second one of the driving signals (M2) (representing a second lowest brightness bit) is subsequently stored and transmitted. Such an operation similarly requires the preparation period (T1). Upon receipt of the driving signal (M2), the LEDs of the LED device are each turned on or off for another driving period associated with the driving signal (M2). In this example, the driving period equals (2*T2). It is noted that a longer driving period is associated with a higher brightness bit, which is associated with a higher level of brightness.
The driving system then stores and transmits each of the remaining driving signals to the LED device, and the LED device is to be driven according to the driving signals in like manner.
However, since the preparation period (T1) and the various driving periods associated with the driving signals are not identical, an efficiency of the LED device may be reduced. For example, in the example as illustrated in FIG. 1, after the LED device is driven by the first one of the driving signals (M1) for the predetermined driving period (T2), the next one of the driving signals (M2) is still in the process of being stored and transmitted, thus leaving the LED device in a non-driven state, in which the LED device is inactive (i.e., does not emit light).
On the other hand, a higher brightness bit corresponds to a longer driving period, and when the driving period associated with a particular driving signal is larger than the time period (T1) for storing and transmitting, the LED device may not be able to receive a next one of the driving signals for quite a while, during which time the driving system is in an idle state.
Both the LED device being inactive and the driving system being in the idle state induce undesired effects, reducing the efficiency of the LED device, and with the longer the LED device is inactive, a resulting overall brightness of the LED device is reduced.
Additionally, a refresh cycle of the conventional LED device is one in which all driving signals are transmitted to the LED device with the LED device operating accordingly. As described above, the longer the idle time, the longer the refresh cycle.